MECHANICAL PROPERTIES OF AAR M128-69-B STEEL PLATE SAMPLES TAKEN FROM INSULATED FIRE TESTED TANK CAR RAX 202

Studies were undertaken to measure the elevated-temperature mechanical properties and to determine the elevated- temperature fracture behavior of selected AAR M128-B steel plates. In addition, the ambient-temperature mechanical properties were measured to determine if the requirements of specification AAR M128-69-B were satisfied. The NBS results of check chemical analyses, hardness surveys, thickness measurements, macroscopic observations, and metallographic analyses of the plate samples had been reported previously. The results of ambient-temperature tensile tests showed that all plate samples met the strength and tensile ductility requirements of specification AAR M128-69-B. The results of hot-tensile tests showed a continuous decrease in strength properties and an increase in tensile ductility as the test temperature was increased from 1100 F to 1250 F. An analysis of stress-rupture data for specimens from all plant samples in the same temperature range indicated that a straight line in a log-log plot of initial stress versus rupture life reasonably represented the data at each test temperature. In the temperature and stress range studied, a decrease in the initial stress of about 20 to 30 percent resulted in a twelvefold increase in rupture life from 15 minutes to three hours. A comparison of the results of the metallographic analysis of hot-tensile and representative stress-rupture specimens with the previously reported metallographic results on the initial rupture site in the failed shell course indicate the presence of the identical fracture mode. This mode is characterized by many intergranular voids which originate primarily at the proeutectoid ferrite-pearlite boundaries. These results confirm the previously reported finding that the initial rupture of the tank car was a stress-rupture crack.

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  • Supplemental Notes:
    • This is the eight in a series of reports on the properties of tank car steels.
  • Corporate Authors:

    National Bureau of Standards

    14th Between E Street and Constitution Avenue, NW
    Washington, DC  United States  20234

    Federal Railroad Administration

    Office of Research and Development, 1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
  • Authors:
    • Early, J G
  • Publication Date: 1976-6

Media Info

  • Features: Figures; References; Tables;
  • Pagination: 82 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00141002
  • Record Type: Publication
  • Source Agency: Federal Railroad Administration
  • Report/Paper Numbers: FRA/OR&D-76-74 Final Rpt.
  • Contract Numbers: DOT-AR-40008
  • Files: TRIS, USDOT
  • Created Date: Oct 26 1976 12:00AM